text: /*
   * INET		An implementation of the TCP/IP protocol suite for the LINUX
   *		operating system.  INET is implemented using the  BSD Socket
   *		interface as the means of communication with the user level.
   *
   *		AF_INET protocol family socket handler.
   *
   * Version:	@(#)af_inet.c	(from sock.c) 1.0.17	06/02/93
   *
   * Authors:	Ross Biro, <bir7@leland.Stanford.Edu>
   *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
   *		Florian La Roche, <flla@stud.uni-sb.de>
   *		Alan Cox, <A.Cox@swansea.ac.uk>
   *
   * Changes (see also sock.c)
   *
   *		A.N.Kuznetsov	:	Socket death error in accept().
   *		John Richardson :	Fix non blocking error in connect()
   *					so sockets that fail to connect
   *					don't return -EINPROGRESS.
   *		Alan Cox	:	Asynchronous I/O support
   *		Alan Cox	:	Keep correct socket pointer on sock structures
   *					when accept() ed
   *		Alan Cox	:	Semantics of SO_LINGER aren't state moved
   *					to close when you look carefully. With
   *					this fixed and the accept bug fixed 
   *					some RPC stuff seems happier.
   *		Niibe Yutaka	:	4.4BSD style write async I/O
   *		Alan Cox, 
   *		Tony Gale 	:	Fixed reuse semantics.
   *		Alan Cox	:	bind() shouldn't abort existing but dead
   *					sockets. Stops FTP netin:.. I hope.
   *		Alan Cox	:	bind() works correctly for RAW sockets. Note
   *					that FreeBSD at least is broken in this respect
   *					so be careful with compatibility tests...
   *
   *		This program is free software; you can redistribute it and/or
   *		modify it under the terms of the GNU General Public License
   *		as published by the Free Software Foundation; either version
   *		2 of the License, or (at your option) any later version.
   */
  
  #include <linux/config.h>
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/kernel.h>
  #include <linux/major.h>
  #include <linux/sched.h>
  #include <linux/timer.h>
  #include <linux/string.h>
  #include <linux/sockios.h>
  #include <linux/net.h>
  #include <linux/fcntl.h>
  #include <linux/mm.h>
  #include <linux/interrupt.h>
  
  #include <asm/segment.h>
  #include <asm/system.h>
  
  #include <linux/inet.h>
  #include <linux/netdevice.h>
  #include "ip.h"
  #include "protocol.h"
  #include "arp.h"
  #include "rarp.h"
  #include "route.h"
  #include "tcp.h"
  #include "udp.h"
  #include <linux/skbuff.h>
  #include "sock.h"
  #include "raw.h"
  #include "icmp.h"
  
  #define min(a,b)	((a)<(b)?(a):(b))
  
  extern struct proto packet_prot;
  
  
  /*
   *	See if a socket number is in use.
   */
   
  static int sk_inuse(struct proto *prot, int num)
  {
  	struct sock *sk;
  
  	for(sk = prot->sock_array[num & (SOCK_ARRAY_SIZE -1 )];
  		sk != NULL;  sk=sk->next) 
  	{
  		if (sk->num == num) 
  			return(1);
  	}
  	return(0);
  }
  
  
  /*
   *	Pick a new socket number
   */
  
  unsigned short get_new_socknum(struct proto *prot, unsigned short base)
  {
  	static int start=0;
  
  	/*
  	 * Used to cycle through the port numbers so the
  	 * chances of a confused connection drop.
  	 */
  	 
  	int i, j;
  	int best = 0;
  	int size = 32767; /* a big num. */
  	struct sock *sk;
  
  	if (base == 0) 
  		base = PROT_SOCK+1+(start % 1024);
  	if (base <= PROT_SOCK) 
  	{
  		base += PROT_SOCK+(start % 1024);
  	}
  
  	/* Now look through the entire array and try to find an empty ptr. */
  	for(i=0; i < SOCK_ARRAY_SIZE; i++) 
  	{
  		j = 0;
  		sk = prot->sock_array[(i+base+1) &(SOCK_ARRAY_SIZE -1)];
  		while(sk != NULL) 
  		{
  			sk = sk->next;
  			j++;
  		}
  		if (j == 0) 
  		{
  			start =(i+1+start )%1024;
  			return(i+base+1);
  		}
  		if (j < size) 
  		{
  			best = i;
  			size = j;
  		}
  	}
  
  	/* Now make sure the one we want is not in use. */
  
  	while(sk_inuse(prot, base +best+1)) 
  	{
  		best += SOCK_ARRAY_SIZE;
  	}
  	return(best+base+1);
  }
  
  /*
   *	Add a socket into the socket tables by number.
   */
  
  void put_sock(unsigned short num, struct sock *sk)
  {
  	struct sock *sk1;
  	struct sock *sk2;
  	int mask;
  	unsigned long flags;
  
  	sk->num = num;
  	sk->next = NULL;
  	num = num &(SOCK_ARRAY_SIZE -1);
  
  	/* We can't have an interrupt re-enter here. */
  	save_flags(flags);
  	cli();
  
  	sk->prot->inuse += 1;
  	if (sk->prot->highestinuse < sk->prot->inuse)
  		sk->prot->highestinuse = sk->prot->inuse;
  
  	if (sk->prot->sock_array[num] == NULL) 
  	{
  		sk->prot->sock_array[num] = sk;
  		restore_flags(flags);
  		return;
  	}
  	restore_flags(flags);
  	for(mask = 0xff000000; mask != 0xffffffff; mask = (mask >> 8) | mask) 
  	{
  		if ((mask & sk->saddr) &&
  		    (mask & sk->saddr) != (mask & 0xffffffff)) 
  		{
  			mask = mask << 8;
  			break;
  		}
  	}
  	cli();
  	sk1 = sk->prot->sock_array[num];
  	for(sk2 = sk1; sk2 != NULL; sk2=sk2->next) 
  	{
  		if (!(sk2->saddr & mask)) 
  		{
  			if (sk2 == sk1) 
  			{
  				sk->next = sk->prot->sock_array[num];
  				sk->prot->sock_array[num] = sk;
  				sti();
  				return;
  			}
  			sk->next = sk2;
  			sk1->next= sk;
  			sti();
  			return;
  		}
  		sk1 = sk2;
  	}
  
  	/* Goes at the end. */
  	sk->next = NULL;
  	sk1->next = sk;
  	sti();
  }
  
  /*
   *	Remove a socket from the socket tables.
   */
  
  static void remove_sock(struct sock *sk1)
  {
  	struct sock *sk2;
  	unsigned long flags;
  
  	if (!sk1->prot) 
  	{
  		printk("sock.c: remove_sock: sk1->prot == NULL\n");
  		return;
  	}
  
  	/* We can't have this changing out from under us. */
  	save_flags(flags);
  	cli();
  	sk2 = sk1->prot->sock_array[sk1->num &(SOCK_ARRAY_SIZE -1)];
  	if (sk2 == sk1) 
  	{
  		sk1->prot->inuse -= 1;
  		sk1->prot->sock_array[sk1->num &(SOCK_ARRAY_SIZE -1)] = sk1->next;
  		restore_flags(flags);
  		return;
  	}
  
  	while(sk2 && sk2->next != sk1) 
  	{
  		sk2 = sk2->next;
  	}
  
  	if (sk2) 
  	{
  		sk1->prot->inuse -= 1;
  		sk2->next = sk1->next;
  		restore_flags(flags);
  		return;
  	}
  	restore_flags(flags);
  }
  
  /*
   *	Destroy an AF_INET socket
   */
   
  void destroy_sock(struct sock *sk)
  {
  	struct sk_buff *skb;
  
    	sk->inuse = 1;			/* just to be safe. */
  
    	/* In case it's sleeping somewhere. */
    	if (!sk->dead) 
    		sk->write_space(sk);
  
    	remove_sock(sk);
    
    	/* Now we can no longer get new packets. */
    	delete_timer(sk);
    	/* Nor send them */
  	del_timer(&sk->retransmit_timer);
  	
  	while ((skb = tcp_dequeue_partial(sk)) != NULL) {
  		IS_SKB(skb);
  		kfree_skb(skb, FREE_WRITE);
  	}
  
  	/* Cleanup up the write buffer. */
    	while((skb = skb_dequeue(&sk->write_queue)) != NULL) {
  		IS_SKB(skb);
  		kfree_skb(skb, FREE_WRITE);
    	}
    	
    	/*
    	 *	Don't discard received data until the user side kills its
    	 *	half of the socket.
    	 */
  
  	if (sk->dead) 
  	{
    		while((skb=skb_dequeue(&sk->receive_queue))!=NULL) 
    		{
  		/*
  		 * This will take care of closing sockets that were
  		 * listening and didn't accept everything.
  		 */
  			if (skb->sk != NULL && skb->sk != sk) 
  			{
  				IS_SKB(skb);
  				skb->sk->dead = 1;
  				skb->sk->prot->close(skb->sk, 0);
  			}
  			IS_SKB(skb);
  			kfree_skb(skb, FREE_READ);
  		}
  	}	
  
  	/* Now we need to clean up the send head. */
  	cli();
  	for(skb = sk->send_head; skb != NULL; )
  	{
  		struct sk_buff *skb2;
  
  		/*
  		 * We need to remove skb from the transmit queue,
  		 * or maybe the arp queue.
  		 */
  		if (skb->next  && skb->prev) {
  /*			printk("destroy_sock: unlinked skb\n");*/
  			IS_SKB(skb);
  			skb_unlink(skb);
  		}
  		skb->dev = NULL;
  		skb2 = skb->link3;
  		kfree_skb(skb, FREE_WRITE);
  		skb = skb2;
  	}
  	sk->send_head = NULL;
  	sti();
  
    	/* And now the backlog. */
    	while((skb=skb_dequeue(&sk->back_log))!=NULL) 
    	{
  		/* this should never happen. */
  /*		printk("cleaning back_log\n");*/
  		kfree_skb(skb, FREE_READ);
  	}
  
  	/* Now if it has a half accepted/ closed socket. */
  	if (sk->pair) 
  	{
  		sk->pair->dead = 1;
  		sk->pair->prot->close(sk->pair, 0);
  		sk->pair = NULL;
    	}
  
  	/*
  	 * Now if everything is gone we can free the socket
  	 * structure, otherwise we need to keep it around until
  	 * everything is gone.
  	 */
  
  	  if (sk->dead && sk->rmem_alloc == 0 && sk->wmem_alloc == 0) 
  	  {
  		kfree_s((void *)sk,sizeof(*sk));
  	  } 
  	  else 
  	  {
  		/* this should never happen. */
  		/* actually it can if an ack has just been sent. */
  		sk->destroy = 1;
  		sk->ack_backlog = 0;
  		sk->inuse = 0;
  		reset_timer(sk, TIME_DESTROY, SOCK_DESTROY_TIME);
    	}
  }
  
  /*
   *	The routines beyond this point handle the behaviour of an AF_INET
   *	socket object. Mostly it punts to the subprotocols of IP to do
   *	the work.
   */
   
  static int inet_fcntl(struct socket *sock, unsigned int cmd, unsigned long arg)
  {
  	struct sock *sk;
  
  	sk = (struct sock *) sock->data;
  
  	switch(cmd) 
  	{
  		case F_SETOWN:
  			/*
  			 * This is a little restrictive, but it's the only
  			 * way to make sure that you can't send a sigurg to
  			 * another process.
  			 */
  			if (!suser() && current->pgrp != -arg &&
  				current->pid != arg) return(-EPERM);
  			sk->proc = arg;
  			return(0);
  		case F_GETOWN:
  			return(sk->proc);
  		default:
  			return(-EINVAL);
  	}
  }
  
  /*
   *	Set socket options on an inet socket.
   */
   
  static int inet_setsockopt(struct socket *sock, int level, int optname,
  		    char *optval, int optlen)
  {
    	struct sock *sk = (struct sock *) sock->data;  
  	if (level == SOL_SOCKET)
  		return sock_setsockopt(sk,level,optname,optval,optlen);
  	if (sk->prot->setsockopt==NULL)
  		return(-EOPNOTSUPP);
  	else
  		return sk->prot->setsockopt(sk,level,optname,optval,optlen);
  }
  
  /*
   *	Get a socket option on an AF_INET socket.
   */
  
  static int inet_getsockopt(struct socket *sock, int level, int optname,
  		    char *optval, int *optlen)
  {
    	struct sock *sk = (struct sock *) sock->data;  	
    	if (level == SOL_SOCKET) 
    		return sock_getsockopt(sk,level,optname,optval,optlen);
    	if(sk->prot->getsockopt==NULL)  	
    		return(-EOPNOTSUPP);
    	else
    		return sk->prot->getsockopt(sk,level,optname,optval,optlen);
  }
  
  /*
   *	Automatically bind an unbound socket.
   */
  
  static int inet_autobind(struct sock *sk)
  {
  	/* We may need to bind the socket. */
  	if (sk->num == 0) 
  	{
  		sk->num = get_new_socknum(sk->prot, 0);
  		if (sk->num == 0) 
  			return(-EAGAIN);
  		put_sock(sk->num, sk);
  		sk->dummy_th.source = ntohs(sk->num);
  	}
  	return 0;
  }
  
  /*
   *	Move a socket into listening state.
   */
   
  static int inet_listen(struct socket *sock, int backlog)
  {
  	struct sock *sk = (struct sock *) sock->data;
  
  	if(inet_autobind(sk)!=0)
  		return -EAGAIN;
  
  	/* We might as well re use these. */ 
  	/*
  	 * note that the backlog is "unsigned char", so truncate it
  	 * somewhere. We might as well truncate it to what everybody
  	 * else does..
  	 */
  	if (backlog > 5)
  		backlog = 5;
  	sk->max_ack_backlog = backlog;
  	if (sk->state != TCP_LISTEN)
  	{
  		sk->ack_backlog = 0;
  		sk->state = TCP_LISTEN;
  	}
  	return(0);
  }
  
  /*
   *	Default callbacks for user INET sockets. These just wake up
   *	the user owning the socket.
   */
  
  static void def_callback1(struct sock *sk)
  {
  	if(!sk->dead)
  		wake_up_interruptible(sk->sleep);
  }
  
  static void def_callback2(struct sock *sk,int len)
  {
  	if(!sk->dead)
  	{
  		wake_up_interruptible(sk->sleep);
  		sock_wake_async(sk->socket, 1);
  	}
  }
  
  static void def_callback3(struct sock *sk)
  {
  	if(!sk->dead)
  	{
  		wake_up_interruptible(sk->sleep);
  		sock_wake_async(sk->socket, 2);
  	}
  }
  
  /*
   *	Create an inet socket.
   *
   *	FIXME: Gcc would generate much better code if we set the parameters
   *	up in in-memory structure order. Gcc68K even more so
   */
  
  static int inet_create(struct socket *sock, int protocol)
  {
  	struct sock *sk;
  	struct proto *prot;
  	int err;
  
  	sk = (struct sock *) kmalloc(sizeof(*sk), GFP_KERNEL);
  	if (sk == NULL) 
  		return(-ENOBUFS);
  	sk->num = 0;
  	sk->reuse = 0;
  	switch(sock->type) 
  	{
  		case SOCK_STREAM:
  		case SOCK_SEQPACKET:
  			if (protocol && protocol != IPPROTO_TCP) 
  			{
  				kfree_s((void *)sk, sizeof(*sk));
  				return(-EPROTONOSUPPORT);
  			}
  			protocol = IPPROTO_TCP;
  			sk->no_check = TCP_NO_CHECK;
  			prot = &tcp_prot;
  			break;
  
  		case SOCK_DGRAM:
  			if (protocol && protocol != IPPROTO_UDP) 
  			{
  				kfree_s((void *)sk, sizeof(*sk));
  				return(-EPROTONOSUPPORT);
  			}
  			protocol = IPPROTO_UDP;
  			sk->no_check = UDP_NO_CHECK;
  			prot=&udp_prot;
  			break;
        
  		case SOCK_RAW:
  			if (!suser()) 
  			{
  				kfree_s((void *)sk, sizeof(*sk));
  				return(-EPERM);
  			}
  			if (!protocol) 
  			{
  				kfree_s((void *)sk, sizeof(*sk));
  				return(-EPROTONOSUPPORT);
  			}
  			prot = &raw_prot;
  			sk->reuse = 1;
  			sk->no_check = 0;	/*
  						 * Doesn't matter no checksum is
  						 * performed anyway.
  						 */
  			sk->num = protocol;
  			break;
  
  		case SOCK_PACKET:
  			if (!suser()) 
  			{
  				kfree_s((void *)sk, sizeof(*sk));
  				return(-EPERM);
  			}
  			if (!protocol) 
  			{
  				kfree_s((void *)sk, sizeof(*sk));
  				return(-EPROTONOSUPPORT);
  			}
  			prot = &packet_prot;
  			sk->reuse = 1;
  			sk->no_check = 0;	/* Doesn't matter no checksum is
  						 * performed anyway.
  						 */
  			sk->num = protocol;
  			break;
  
  		default:
  			kfree_s((void *)sk, sizeof(*sk));
  			return(-ESOCKTNOSUPPORT);
  	}
  	sk->socket = sock;
  #ifdef CONFIG_TCP_NAGLE_OFF
  	sk->nonagle = 1;
  #else    
  	sk->nonagle = 0;
  #endif  
  	sk->type = sock->type;
  	sk->stamp.tv_sec=0;
  	sk->protocol = protocol;
  	sk->wmem_alloc = 0;
  	sk->rmem_alloc = 0;
  	sk->sndbuf = SK_WMEM_MAX;
  	sk->rcvbuf = SK_RMEM_MAX;
  	sk->pair = NULL;
  	sk->opt = NULL;
  	sk->write_seq = 0;
  	sk->acked_seq = 0;
  	sk->copied_seq = 0;
  	sk->fin_seq = 0;
  	sk->urg_seq = 0;
  	sk->urg_data = 0;
  	sk->proc = 0;
  	sk->rtt = 0;				/*TCP_WRITE_TIME << 3;*/
  	sk->rto = TCP_TIMEOUT_INIT;		/*TCP_WRITE_TIME*/
  	sk->mdev = 0;
  	sk->backoff = 0;
  	sk->packets_out = 0;
  	sk->cong_window = 1; /* start with only sending one packet at a time. */
  	sk->cong_count = 0;
  	sk->ssthresh = 0;
  	sk->max_window = 0;
  	sk->urginline = 0;
  	sk->intr = 0;
  	sk->linger = 0;
  	sk->destroy = 0;
  	sk->priority = 1;
  	sk->shutdown = 0;
  	sk->keepopen = 0;
  	sk->zapped = 0;
  	sk->done = 0;
  	sk->ack_backlog = 0;
  	sk->window = 0;
  	sk->bytes_rcv = 0;
  	sk->state = TCP_CLOSE;
  	sk->dead = 0;
  	sk->ack_timed = 0;
  	sk->partial = NULL;
  	sk->user_mss = 0;
  	sk->debug = 0;
  
  	/* this is how many unacked bytes we will accept for this socket.  */
  	sk->max_unacked = 2048; /* needs to be at most 2 full packets. */
  
  	/* how many packets we should send before forcing an ack. 
  	   if this is set to zero it is the same as sk->delay_acks = 0 */
  	sk->max_ack_backlog = 0;
  	sk->inuse = 0;
  	sk->delay_acks = 0;
  	skb_queue_head_init(&sk->write_queue);
  	skb_queue_head_init(&sk->receive_queue);
  	sk->mtu = 576;
  	sk->prot = prot;
  	sk->sleep = sock->wait;
  	sk->daddr = 0;
  	sk->saddr = 0 /* ip_my_addr() */;
  	sk->err = 0;
  	sk->next = NULL;
  	sk->pair = NULL;
  	sk->send_tail = NULL;
  	sk->send_head = NULL;
  	sk->timeout = 0;
  	sk->broadcast = 0;
  	sk->localroute = 0;
  	init_timer(&sk->timer);
  	init_timer(&sk->retransmit_timer);
  	sk->timer.data = (unsigned long)sk;
  	sk->timer.function = &net_timer;
  	skb_queue_head_init(&sk->back_log);
  	sk->blog = 0;
  	sock->data =(void *) sk;
  	sk->dummy_th.doff = sizeof(sk->dummy_th)/4;
  	sk->dummy_th.res1=0;
  	sk->dummy_th.res2=0;
  	sk->dummy_th.urg_ptr = 0;
  	sk->dummy_th.fin = 0;
  	sk->dummy_th.syn = 0;
  	sk->dummy_th.rst = 0;
  	sk->dummy_th.psh = 0;
  	sk->dummy_th.ack = 0;
  	sk->dummy_th.urg = 0;
  	sk->dummy_th.dest = 0;
  	sk->ip_tos=0;
  	sk->ip_ttl=64;
  #ifdef CONFIG_IP_MULTICAST
  	sk->ip_mc_loop=1;
  	sk->ip_mc_ttl=1;
  	*sk->ip_mc_name=0;
  	sk->ip_mc_list=NULL;
  #endif
    	
  	sk->state_change = def_callback1;
  	sk->data_ready = def_callback2;
  	sk->write_space = def_callback3;
  	sk->error_report = def_callback1;
  
  	if (sk->num) 
  	{
  	/*
  	 * It assumes that any protocol which allows
  	 * the user to assign a number at socket
  	 * creation time automatically
  	 * shares.
  	 */
  		put_sock(sk->num, sk);
  		sk->dummy_th.source = ntohs(sk->num);
  	}
  
  	if (sk->prot->init) 
  	{
  		err = sk->prot->init(sk);
  		if (err != 0) 
  		{
  			destroy_sock(sk);
  			return(err);
  		}
  	}
  	return(0);
  }
  
  
  /*
   *	Duplicate a socket.
   */
   
  static int inet_dup(struct socket *newsock, struct socket *oldsock)
  {
  	return(inet_create(newsock,((struct sock *)(oldsock->data))->protocol));
  }
  
  /*
   * Return 1 if we still have things to send in our buffers.
   */
  static inline int closing(struct sock * sk)
  {
  	switch (sk->state) {
  		case TCP_FIN_WAIT1:
  		case TCP_CLOSING:
  		case TCP_LAST_ACK:
  			return 1;
  	}
  	return 0;
  }
  
  
  /*
   *	The peer socket should always be NULL (or else). When we call this
   *	function we are destroying the object and from then on nobody
   *	should refer to it.
   */
   
  static int inet_release(struct socket *sock, struct socket *peer)
  {
  	struct sock *sk = (struct sock *) sock->data;
  	if (sk == NULL) 
  		return(0);
  
  	sk->state_change(sk);
  
  	/* Start closing the connection.  This may take a while. */
  
  #ifdef CONFIG_IP_MULTICAST
  	/* Applications forget to leave groups before exiting */
  	ip_mc_drop_socket(sk);
  #endif
  	/*
  	 * If linger is set, we don't return until the close
  	 * is complete.  Other wise we return immediately. The
  	 * actually closing is done the same either way.
  	 *
  	 * If the close is due to the process exiting, we never
  	 * linger..
  	 */
  
  	if (sk->linger == 0 || (current->flags & PF_EXITING))
  	{
  		sk->prot->close(sk,0);
  		sk->dead = 1;
  	} 
  	else 
  	{
  		sk->prot->close(sk, 0);
  		cli();
  		if (sk->lingertime)
  			current->timeout = jiffies + HZ*sk->lingertime;
  		while(closing(sk) && current->timeout>0) 
  		{
  			interruptible_sleep_on(sk->sleep);
  			if (current->signal & ~current->blocked) 
  			{
  				break;
  #if 0
  				/* not working now - closes can't be restarted */
  				sti();
  				current->timeout=0;
  				return(-ERESTARTSYS);
  #endif
  			}
  		}
  		current->timeout=0;
  		sti();
  		sk->dead = 1;
  	}
  	sk->inuse = 1;
  
  	/* This will destroy it. */
  	release_sock(sk);
  	sock->data = NULL;
  	sk->socket = NULL;
  	return(0);
  }
  
  
  /* this needs to be changed to disallow
     the rebinding of sockets.   What error
     should it return? */
  
  static int inet_bind(struct socket *sock, struct sockaddr *uaddr,
  	       int addr_len)
  {
  	struct sockaddr_in *addr=(struct sockaddr_in *)uaddr;
  	struct sock *sk=(struct sock *)sock->data, *sk2;
  	unsigned short snum = 0 /* Stoopid compiler.. this IS ok */;
  	int chk_addr_ret;
  
  	/* check this error. */
  	if (sk->state != TCP_CLOSE)
  		return(-EIO);
  	if(addr_len<sizeof(struct sockaddr_in))
  		return -EINVAL;
  		
  	if(sock->type != SOCK_RAW)
  	{
  		if (sk->num != 0) 
  			return(-EINVAL);
  
  		snum = ntohs(addr->sin_port);
  
  		/*
  		 * We can't just leave the socket bound wherever it is, it might
  		 * be bound to a privileged port. However, since there seems to
  		 * be a bug here, we will leave it if the port is not privileged.
  		 */
  		if (snum == 0) 
  		{
  			snum = get_new_socknum(sk->prot, 0);
  		}
  		if (snum < PROT_SOCK && !suser()) 
  			return(-EACCES);
  	}
  	
  	chk_addr_ret = ip_chk_addr(addr->sin_addr.s_addr);
  	if (addr->sin_addr.s_addr != 0 && chk_addr_ret != IS_MYADDR && chk_addr_ret != IS_MULTICAST)
  		return(-EADDRNOTAVAIL);	/* Source address MUST be ours! */
  	  	
  	if (chk_addr_ret || addr->sin_addr.s_addr == 0)
  		sk->saddr = addr->sin_addr.s_addr;
  	
  	if(sock->type != SOCK_RAW)
  	{
  		/* Make sure we are allowed to bind here. */
  		cli();
  		for(sk2 = sk->prot->sock_array[snum & (SOCK_ARRAY_SIZE -1)];
  					sk2 != NULL; sk2 = sk2->next) 
  		{
  		/* should be below! */
  			if (sk2->num != snum) 
  				continue;
  			if (!sk->reuse)
  			{
  				sti();
  				return(-EADDRINUSE);
  			}
  			
  			if (sk2->num != snum) 
  				continue;		/* more than one */
  			if (sk2->saddr != sk->saddr) 
  				continue;	/* socket per slot ! -FB */
  			if (!sk2->reuse || sk2->state==TCP_LISTEN) 
  			{
  				sti();
  				return(-EADDRINUSE);
  			}
  		}
  		sti();
  
  		remove_sock(sk);
  		put_sock(snum, sk);
  		sk->dummy_th.source = ntohs(sk->num);
  		sk->daddr = 0;
  		sk->dummy_th.dest = 0;
  	}
  	return(0);
  }
  
  /*
   *	Handle sk->err properly. The cli/sti matter.
   */
   
  static int inet_error(struct sock *sk)
  {
  	unsigned long flags;
  	int err;
  	save_flags(flags);
  	cli();	
  	err=sk->err;
  	sk->err=0;
  	restore_flags(flags);
  	return -err;
  }
  
  /*
   *	Connect to a remote host. There is regrettably still a little
   *	TCP 'magic' in here.
   */
   
  static int inet_connect(struct socket *sock, struct sockaddr * uaddr,
  		  int addr_len, int flags)
  {
  	struct sock *sk=(struct sock *)sock->data;
  	int err;
  	sock->conn = NULL;
  
  	if (sock->state == SS_CONNECTING && tcp_connected(sk->state))
  	{
  		sock->state = SS_CONNECTED;
  		/* Connection completing after a connect/EINPROGRESS/select/connect */
  		return 0;	/* Rock and roll */
  	}
  
  	if (sock->state == SS_CONNECTING && sk->protocol == IPPROTO_TCP && (flags & O_NONBLOCK))
  		return -EALREADY;	/* Connecting is currently in progress */
    	
  	if (sock->state != SS_CONNECTING) 
  	{
  		/* We may need to bind the socket. */
  		if(inet_autobind(sk)!=0)
  			return(-EAGAIN);
  		if (sk->prot->connect == NULL) 
  			return(-EOPNOTSUPP);
  		err = sk->prot->connect(sk, (struct sockaddr_in *)uaddr, addr_len);
  		if (err < 0) 
  			return(err);
    		sock->state = SS_CONNECTING;
  	}
  	
  	if (sk->state > TCP_FIN_WAIT2 && sock->state==SS_CONNECTING)
  	{
  		sock->state=SS_UNCONNECTED;
  		cli();
  		err=sk->err;
  		sk->err=0;
  		sti();
  		return -err;
  	}
  
  	if (sk->state != TCP_ESTABLISHED &&(flags & O_NONBLOCK)) 
  	  	return(-EINPROGRESS);
  
  	cli(); /* avoid the race condition */
  	while(sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV) 
  	{
  		interruptible_sleep_on(sk->sleep);
  		if (current->signal & ~current->blocked) 
  		{
  			sti();
  			return(-ERESTARTSYS);
  		}
  		/* This fixes a nasty in the tcp/ip code. There is a hideous hassle with
  		   icmp error packets wanting to close a tcp or udp socket. */
  		if(sk->err && sk->protocol == IPPROTO_TCP)
  		{
  			sti();
  			sock->state = SS_UNCONNECTED;
  			err = -sk->err;
  			sk->err=0;
  			return err; /* set by tcp_err() */
  		}
  	}
  	sti();
  	sock->state = SS_CONNECTED;
  
  	if (sk->state != TCP_ESTABLISHED && sk->err) 
  	{
  		sock->state = SS_UNCONNECTED;
  		err=sk->err;
  		sk->err=0;
  		return(-err);
  	}
  	return(0);
  }
  
  
  static int inet_socketpair(struct socket *sock1, struct socket *sock2)
  {
  	 return(-EOPNOTSUPP);
  }
  
  
  /*
   *	Accept a pending connection. The TCP layer now gives BSD semantics.
   */
  
  static int inet_accept(struct socket *sock, struct socket *newsock, int flags)
  {
  	struct sock *sk1, *sk2;
  	int err;
  
  	sk1 = (struct sock *) sock->data;
  
  	/*
  	 * We've been passed an extra socket.
  	 * We need to free it up because the tcp module creates
  	 * its own when it accepts one.
  	 */
  	if (newsock->data)
  	{
  	  	struct sock *sk=(struct sock *)newsock->data;
  	  	newsock->data=NULL;
  	  	sk->dead = 1;
  	  	destroy_sock(sk);
  	}
    
  	if (sk1->prot->accept == NULL) 
  		return(-EOPNOTSUPP);
  
  	/* Restore the state if we have been interrupted, and then returned. */
  	if (sk1->pair != NULL ) 
  	{
  		sk2 = sk1->pair;
  		sk1->pair = NULL;
  	} 
  	else
  	{
  		sk2 = sk1->prot->accept(sk1,flags);
  		if (sk2 == NULL) 
  		{
  			if (sk1->err <= 0)
  				printk("Warning sock.c:sk1->err <= 0.  Returning non-error.\n");
  			err=sk1->err;
  			sk1->err=0;
  			return(-err);
  		}
  	}
  	newsock->data = (void *)sk2;
  	sk2->sleep = newsock->wait;
  	sk2->socket = newsock;
  	newsock->conn = NULL;
  	if (flags & O_NONBLOCK) 
  		return(0);
  
  	cli(); /* avoid the race. */
  	while(sk2->state == TCP_SYN_RECV) 
  	{
  		interruptible_sleep_on(sk2->sleep);
  		if (current->signal & ~current->blocked) 
  		{
  			sti();
  			sk1->pair = sk2;
  			sk2->sleep = NULL;
  			sk2->socket=NULL;
  			newsock->data = NULL;
  			return(-ERESTARTSYS);
  		}
  	}
  	sti();
  
  	if (sk2->state != TCP_ESTABLISHED && sk2->err > 0) 
  	{
  		err = -sk2->err;
  		sk2->err=0;
  		sk2->dead=1;	/* ANK */
  		destroy_sock(sk2);
  		newsock->data = NULL;
  		return(err);
  	}
  	newsock->state = SS_CONNECTED;
  	return(0);
  }
  
  
  /*
   *	This does both peername and sockname.
   */
   
  static int inet_getname(struct socket *sock, struct sockaddr *uaddr,
  		 int *uaddr_len, int peer)
  {
  	struct sockaddr_in *sin=(struct sockaddr_in *)uaddr;
  	struct sock *sk;
    
  	sin->sin_family = AF_INET;
  	sk = (struct sock *) sock->data;
  	if (peer) 
  	{
  		if (!tcp_connected(sk->state)) 
  			return(-ENOTCONN);
  		sin->sin_port = sk->dummy_th.dest;
  		sin->sin_addr.s_addr = sk->daddr;
  	} 
  	else 
  	{
  		sin->sin_port = sk->dummy_th.source;
  		if (sk->saddr == 0) 
  			sin->sin_addr.s_addr = ip_my_addr();
  		else 
  			sin->sin_addr.s_addr = sk->saddr;
  	}
  	*uaddr_len = sizeof(*sin);
  	return(0);
  }
  
  
  /*
   *	The assorted BSD I/O operations
   */
  
  static int inet_recvfrom(struct socket *sock, void *ubuf, int size, int noblock, 
  		   unsigned flags, struct sockaddr *sin, int *addr_len )
  {
  	struct sock *sk = (struct sock *) sock->data;
  	
  	if (sk->prot->recvfrom == NULL) 
  		return(-EOPNOTSUPP);
  	if(sk->err)
  		return inet_error(sk);
  	/* We may need to bind the socket. */
  	if(inet_autobind(sk)!=0)
  		return(-EAGAIN);
  	return(sk->prot->recvfrom(sk, (unsigned char *) ubuf, size, noblock, flags,
  			     (struct sockaddr_in*)sin, addr_len));
  }
  
  
  static int inet_recv(struct socket *sock, void *ubuf, int size, int noblock,
  	  unsigned flags)
  {
  	/* BSD explicitly states these are the same - so we do it this way to be sure */
  	return inet_recvfrom(sock,ubuf,size,noblock,flags,NULL,NULL);
  }
  
  static int inet_read(struct socket *sock, char *ubuf, int size, int noblock)
  {
  	struct sock *sk = (struct sock *) sock->data;
  	
  	if(sk->err)
  		return inet_error(sk);
  	/* We may need to bind the socket. */
  	if(inet_autobind(sk))
  		return(-EAGAIN);	
  	return(sk->prot->read(sk, (unsigned char *) ubuf, size, noblock, 0));
  }
  
  static int inet_send(struct socket *sock, void *ubuf, int size, int noblock, 
  	       unsigned flags)
  {
  	struct sock *sk = (struct sock *) sock->data;
  	if (sk->shutdown & SEND_SHUTDOWN) 
  	{
  		send_sig(SIGPIPE, current, 1);
  		return(-EPIPE);
  	}
  	if(sk->err)
  		return inet_error(sk);
  	/* We may need to bind the socket. */
  	if(inet_autobind(sk)!=0)
  		return(-EAGAIN);
  	return(sk->prot->write(sk, (unsigned char *) ubuf, size, noblock, flags));
  }
  
  static int inet_write(struct socket *sock, char *ubuf, int size, int noblock)
  {
  	return inet_send(sock,ubuf,size,noblock,0);
  }
  
  static int inet_sendto(struct socket *sock, void *ubuf, int size, int noblock, 
  	    unsigned flags, struct sockaddr *sin, int addr_len)
  {
  	struct sock *sk = (struct sock *) sock->data;
  	if (sk->shutdown & SEND_SHUTDOWN) 
  	{
  		send_sig(SIGPIPE, current, 1);
  		return(-EPIPE);
  	}
  	if (sk->prot->sendto == NULL) 
  		return(-EOPNOTSUPP);
  	if(sk->err)
  		return inet_error(sk);
  	/* We may need to bind the socket. */
  	if(inet_autobind(sk)!=0)
  		return -EAGAIN;
  	return(sk->prot->sendto(sk, (unsigned char *) ubuf, size, noblock, flags, 
  			   (struct sockaddr_in *)sin, addr_len));
  }
  
  
  static int inet_shutdown(struct socket *sock, int how)
  {
  	struct sock *sk=(struct sock*)sock->data;
  
  	/*
  	 * This should really check to make sure
  	 * the socket is a TCP socket. (WHY AC...)
  	 */
  	how++; /* maps 0->1 has the advantage of making bit 1 rcvs and
  		       1->2 bit 2 snds.
  		       2->3 */
  	if ((how & ~SHUTDOWN_MASK) || how==0)	/* MAXINT->0 */
  		return(-EINVAL);
  	if (sock->state == SS_CONNECTING && sk->state == TCP_ESTABLISHED)
  		sock->state = SS_CONNECTED;
  	if (!tcp_connected(sk->state)) 
  		return(-ENOTCONN);
  	sk->shutdown |= how;
  	if (sk->prot->shutdown)
  		sk->prot->shutdown(sk, how);
  	return(0);
  }
  
  
  static int inet_select(struct socket *sock, int sel_type, select_table *wait )
  {
  	struct sock *sk=(struct sock *) sock->data;
  	if (sk->prot->select == NULL) 
  	{
  		return(0);
  	}
  	return(sk->prot->select(sk, sel_type, wait));
  }
  
  /*
   *	ioctl() calls you can issue on an INET socket. Most of these are
   *	device configuration and stuff and very rarely used. Some ioctls
   *	pass on to the socket itself.
   *
   *	NOTE: I like the idea of a module for the config stuff. ie ifconfig
   *	loads the devconfigure module does its configuring and unloads it.
   *	There's a good 20K of config code hanging around the kernel.
   */
  
  static int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
  {
  	struct sock *sk=(struct sock *)sock->data;
  	int err;
  
  	switch(cmd) 
  	{
  		case FIOSETOWN:
  		case SIOCSPGRP:
  			err=verify_area(VERIFY_READ,(int *)arg,sizeof(long));
  			if(err)
  				return err;
  			sk->proc = get_fs_long((int *) arg);
  			return(0);
  		case FIOGETOWN:
  		case SIOCGPGRP:
  			err=verify_area(VERIFY_WRITE,(void *) arg, sizeof(long));
  			if(err)
  				return err;
  			put_fs_long(sk->proc,(int *)arg);
  			return(0);			
  		case SIOCGSTAMP:
  			if(sk->stamp.tv_sec==0)
  				return -ENOENT;
  			err=verify_area(VERIFY_WRITE,(void *)arg,sizeof(struct timeval));
  			if(err)
  				return err;
  			memcpy_tofs((void *)arg,&sk->stamp,sizeof(struct timeval));
  			return 0;
  		case SIOCADDRT: case SIOCADDRTOLD:
  		case SIOCDELRT: case SIOCDELRTOLD:
  			return(ip_rt_ioctl(cmd,(void *) arg));
  		case SIOCDARP:
  		case SIOCGARP:
  		case SIOCSARP:
  			return(arp_ioctl(cmd,(void *) arg));
  #ifdef CONFIG_INET_RARP			
  		case SIOCDRARP:
  		case SIOCGRARP:
  		case SIOCSRARP:
  			return(rarp_ioctl(cmd,(void *) arg));
  #endif
  		case SIOCGIFCONF:
  		case SIOCGIFFLAGS:
  		case SIOCSIFFLAGS:
  		case SIOCGIFADDR:
  		case SIOCSIFADDR:
  
  /* begin multicast support change */
  		case SIOCADDMULTI:
  		case SIOCDELMULTI:
  /* end multicast support change */
  		
  		case SIOCGIFDSTADDR:
  		case SIOCSIFDSTADDR:
  		case SIOCGIFBRDADDR:
  		case SIOCSIFBRDADDR:
  		case SIOCGIFNETMASK:
  		case SIOCSIFNETMASK:
  		case SIOCGIFMETRIC:
  		case SIOCSIFMETRIC:
  		case SIOCGIFMEM:
  		case SIOCSIFMEM:
  		case SIOCGIFMTU:
  		case SIOCSIFMTU:
  		case SIOCSIFLINK:
  		case SIOCGIFHWADDR:
  		case SIOCSIFHWADDR:
  		case OLD_SIOCGIFHWADDR:
  		case SIOCSIFMAP:
  		case SIOCGIFMAP:
  		case SIOCSIFSLAVE:
  		case SIOCGIFSLAVE:
  			return(dev_ioctl(cmd,(void *) arg));
  
  		default:
  			if ((cmd >= SIOCDEVPRIVATE) &&
  			   (cmd <= (SIOCDEVPRIVATE + 15)))
  				return(dev_ioctl(cmd,(void *) arg));
  
  			if (sk->prot->ioctl==NULL) 
  				return(-EINVAL);
  			return(sk->prot->ioctl(sk, cmd, arg));
  	}
  	/*NOTREACHED*/
  	return(0);
  }
  
  /*
   * This routine must find a socket given a TCP or UDP header.
   * Everything is assumed to be in net order.
   *
   * We give priority to more closely bound ports: if some socket
   * is bound to a particular foreign address, it will get the packet
   * rather than somebody listening to any address..
   */
  
  struct sock *get_sock(struct proto *prot, unsigned short num,
  				unsigned long raddr,
  				unsigned short rnum, unsigned long laddr)
  {
  	struct sock *s;
  	struct sock *result = NULL;
  	int badness = -1;
  	unsigned short hnum;
  
  	hnum = ntohs(num);
  
  	/*
  	 * SOCK_ARRAY_SIZE must be a power of two.  This will work better
  	 * than a prime unless 3 or more sockets end up using the same
  	 * array entry.  This should not be a problem because most
  	 * well known sockets don't overlap that much, and for
  	 * the other ones, we can just be careful about picking our
  	 * socket number when we choose an arbitrary one.
  	 */
  
  	for(s = prot->sock_array[hnum & (SOCK_ARRAY_SIZE - 1)];
  			s != NULL; s = s->next) 
  	{
  		int score = 0;
  
  		if (s->num != hnum) 
  			continue;
  
  		if(s->dead && (s->state == TCP_CLOSE))
  			continue;
  		/* local address matches? */
  		if (s->saddr) {
  			if (s->saddr != laddr)
  				continue;
  			score++;
  		}
  		/* remote address matches? */
  		if (s->daddr) {
  			if (s->daddr != raddr)
  				continue;
  			score++;
  		}
  		/* remote port matches? */
  		if (s->dummy_th.dest) {
  			if (s->dummy_th.dest != rnum)
  				continue;
  			score++;
  		}
  		/* perfect match? */
  		if (score == 3)
  			return s;
  		/* no, check if this is the best so far.. */
  		if (score <= badness)
  			continue;
  		result = s;
  		badness = score;
    	}
    	return result;
  }
  
  /*
   *	Deliver a datagram to raw sockets.
   */
   
  struct sock *get_sock_raw(struct sock *sk, 
  				unsigned short num,
  				unsigned long raddr,
  				unsigned long laddr)
  {
  	struct sock *s;
  
  	s=sk;
  
  	for(; s != NULL; s = s->next) 
  	{
  		if (s->num != num) 
  			continue;
  		if(s->dead && (s->state == TCP_CLOSE))
  			continue;
  		if(s->daddr && s->daddr!=raddr)
  			continue;
   		if(s->saddr  && s->saddr!=laddr)
  			continue;
  		return(s);
    	}
    	return(NULL);
  }
  
  #ifdef CONFIG_IP_MULTICAST
  /*
   *	Deliver a datagram to broadcast/multicast sockets.
   */
   
  struct sock *get_sock_mcast(struct sock *sk, 
  				unsigned short num,
  				unsigned long raddr,
  				unsigned short rnum, unsigned long laddr)
  {
  	struct sock *s;
  	unsigned short hnum;
  
  	hnum = ntohs(num);
  
  	/*
  	 * SOCK_ARRAY_SIZE must be a power of two.  This will work better
  	 * than a prime unless 3 or more sockets end up using the same
  	 * array entry.  This should not be a problem because most
  	 * well known sockets don't overlap that much, and for
  	 * the other ones, we can just be careful about picking our
  	 * socket number when we choose an arbitrary one.
  	 */
  	
  	s=sk;
  
  	for(; s != NULL; s = s->next) 
  	{
  		if (s->num != hnum) 
  			continue;
  		if(s->dead && (s->state == TCP_CLOSE))
  			continue;
  		if(s->daddr && s->daddr!=raddr)
  			continue;
  		if (s->dummy_th.dest != rnum && s->dummy_th.dest != 0) 
  			continue;
   		if(s->saddr  && s->saddr!=laddr)
  			continue;
  		return(s);
    	}
    	return(NULL);
  }
  
  #endif
  
  static struct proto_ops inet_proto_ops = {
  	AF_INET,
  
  	inet_create,
  	inet_dup,
  	inet_release,
  	inet_bind,
  	inet_connect,
  	inet_socketpair,
  	inet_accept,
  	inet_getname, 
  	inet_read,
  	inet_write,
  	inet_select,
  	inet_ioctl,
  	inet_listen,
  	inet_send,
  	inet_recv,
  	inet_sendto,
  	inet_recvfrom,
  	inet_shutdown,
  	inet_setsockopt,
  	inet_getsockopt,
  	inet_fcntl,
  };
  
  extern unsigned long seq_offset;
  
  /*
   *	Called by socket.c on kernel startup.  
   */
   
  void inet_proto_init(struct net_proto *pro)
  {
  	struct inet_protocol *p;
  	int i;
  
  
  	printk("Swansea University Computer Society TCP/IP for NET3.019\n");
  
  	/*
  	 *	Tell SOCKET that we are alive... 
  	 */
     
    	(void) sock_register(inet_proto_ops.family, &inet_proto_ops);
  
    	seq_offset = CURRENT_TIME*250;
  
  	/*
  	 *	Add all the protocols. 
  	 */
  	 
  	for(i = 0; i < SOCK_ARRAY_SIZE; i++) 
  	{
  		tcp_prot.sock_array[i] = NULL;
  		udp_prot.sock_array[i] = NULL;
  		raw_prot.sock_array[i] = NULL;
    	}
  	tcp_prot.inuse = 0;
  	tcp_prot.highestinuse = 0;
  	udp_prot.inuse = 0;
  	udp_prot.highestinuse = 0;
  	raw_prot.inuse = 0;
  	raw_prot.highestinuse = 0;
  
  	printk("IP Protocols: ");
  	for(p = inet_protocol_base; p != NULL;) 
  	{
  		struct inet_protocol *tmp = (struct inet_protocol *) p->next;
  		inet_add_protocol(p);
  		printk("%s%s",p->name,tmp?", ":"\n");
  		p = tmp;
  	}
  	/*
  	 *	Set the ARP module up
  	 */
  	arp_init();
    	/*
    	 *	Set the IP module up
    	 */
  	ip_init();
  }
  
  